Some owners search their whole lives for a Cox Plate runner.

Former Cronulla Sharks captain Paul Gallen has found one with his first racehorse.

The rugby league great part-owns Te Akau Shark and will travel down to Melbourne to watch the Jamie Richards-trained New Zealander run in the weight-for-age Group One feature (2040m) at Moonee Valley on Saturday.

Gallen, who hung up the boots this year after 20 seasons, is well aware of the long odds of having such instant success in the racing game.

"I can almost feel the daggers in my back," Gallen told the Big Sports Breakfast.

"I've been told it's something like 5000-1 to have a horse that's good enough to run in the Cox Plate, let alone it being your first horse.

"It's terribly lucky."

Gallen bought a stake in the chestnut gelding after a friend had a chance encounter with Te Akau Racing principal David Ellis while on holiday in Hawaii.

The 38-year-old ended up having the final say on the five-year-old's name as he led Cronulla past Melbourne in the 2016 NRL grand final.

"Another one of the owners is a massive Melbourne Storm fan," Gallen said.

"It was going to be Te Akau something and we said 'well OK whoever wins the grand final, we'll name it after'.

"Thankfully we beat the Storm so it became Te Akau Shark."

Not even drawing barrier 18 of 18 can dint Gallen's optimism and he cites the gelding's finishing burst as his biggest asset as when he flashed home in the Epsom Handicap.

"They probably want him to be sort of midfield and if he can find some cover and get a good run on the straight, the way he comes home, anything could happen," he said.

Te Akau Shark is rated a $16 chance with Japanese raider Lys Gracieux ($3.80) a clear favourite from Mystic Journey ($6.50) and Castelvecchio ($7.50).